This broke float textures, which were actually used by some shaders.
There were probably some other bugs as well.
Lots of code can be avoided by using ra_tex_params directly, so do that.
The main change is that COMPONENT/FORMAT are replaced by a single FORMAT
directive, which takes different parameters now. Due to the mess with
16/32 bit float textures, and because we want to support other APIs than
just GL in the future, it's not really clear how this should be handled,
and the nice component/type separation makes things actually harder. So
just jump the gun and use the ra_format.name names, which were
originally meant mostly for debugging. (This is probably something that
will be regretted later.)
Still only superficially tested, but seems to work.
Fixes #4708.